David Portas (3/23/2010)
Ed-997158 (3/23/2010)
Thanks. I was just going to ask if "bridge table" didn't already have a different terminology"Associative Entity" is semantic modelling terminology and not a relational database term. I've never found much use in the idea of singling out tables in this way. As far as I see it, a "bridge" or "associative" table can be any table with more than one foreign key. But why do we need a special name for tables with more than one foreign key?
Fundamentally there is just one type of relational table (i.e. a table that properly represents a relation). Any such table represents an N-ary relationship between its attributes and "associative" tables are not a special case in any important respect.
I don't want to get into a modeling food fight, but don't semantics matter? There are some definite classes of relationships (design patterns) that are modeled in a relational database; the many-to-many betweeen tables, which cannot be handled in first normal form and requires the bridge/associative table, is one of these. Recognizing these design patterns and saying "oh, this is one of those and here's how you solve" is important to avoid re-inventing the wheel each time you design a new part of a database.